Security gates are commonly used for various purposes including controlling ingress and egress to residential communities, businesses, and ranch roads. These gates are operated in a variety of ways such as push button digital combinations, remote push buttons, key card reader system, intercom of telephone system, air hose switch, ground loop sensory system, hand-held transmitters, etc., all of which generate a gate opening signal. Gate closure can occur after a predetermined time delay or in response to a gate closure- signal which can be generated in any suitable manner such as by one of the above mentioned systems.
Security gates of this type commonly move horizontally between the open and closed positions. One prior art security gate system of this type includes a gate which pivots about a generally vertical pivot axis between the open and closed positions. However, a gate of this type cannot effectively be used on sloping terrain, and there is a tendency for some vehicle drivers to try to hasten the opening of the gate by pushing on it with their vehicle, and this can damage the gate and its operating mechanism.
Another prior art security gate system employs a gate which is moved linearly between the open and closed positions. This gate system, however, requires substantial space to the side of the roadway for movement of the gate and is more difficult to install and/or use on sloped terrain.
A security gate system utilizing a vertically moveable gate overcomes these disadvantages. In a gate system of this type, the gate is mounted on a supporting structure for pivotal movement about a generally horizontal pivot axis between closed and open positions. Because the gate pivots in a vertical plane, it can be used regardless of the sloping nature of the route or roadway across which the gate extends in the closed position. Also, because the gate pivots vertically there is no need for a large space adjacent the route or roadway for receiving the gate in the open position.
One problem with vertical gate systems is in locking them in the closed position so they are more difficult to open by unauthorized personnel. In this regard, it may be possible for the locking mechanism, which holds the gate in the closed position, to be back driven or unlocked by jiggling the gate. Of course, to the extent that the security gate can be opened by unauthorized personnel, it does not serve its primary function of providing security.
More specifically, one prior art vertical gate system employs a releasable lock for use in releasably holding the gate in a closed position. The lock is movable between a locking position and a releasing position with such movement being brought about by a belt-driven mechanism. Overall, the vertical gate system operates quite well. However, it has been found that the belt drive is subject to being back driven by jiggling the gate, and this can unlock the gate to allow unauthorized personnel to open the gate. This belt is also used to drive the gate between the closed and open positions. It has been found that this belt tends to stretch with use, and this can cause a failure of the releasable lock to release quickly enough with the result that the gate hangs up or fails to open.
In many instances, the incoming and outgoing roads to a community are side by side. In this event, one vertical gate can be used to control ingress and a second vertical gate can be used to control egress. The operating mechanism for each of these two gates can advantageously be provided between the two roadways. However, it has been found that placing two of the supporting structures for the operating mechanisms of two gates in side-by-side relationship in many cases takes more space than is desired.